Pneumatic bumper



T. S. PUKERUD PNEUMATIC BUMPER May 29, 192.8. 1,671,485

Filed Nov. 23. 1922 will/W49,

INVENTOR Thomas 6. Puke/ad.

/ ATTORNEY WITNESSES:

, vide one or more cylinders having Patented May. 29, 1928.

UNITED STATES 1,671,485 PATENT OFFICE.

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' PNEUMATIC BUMPER.

Application filed November 28, 1822'. Serial No. 602,783.

This invention relates to trolley structures, more especially to those which are adapted to be held in extended position by air pressure or the like.

In trolleys of this type, generally known as pantograph trolleys, it 1s usual to profp1s ons therein so engaging with a system 0 levers that, upon the introduction of air thereinto' to move the pistons, the system of levers is actuated and caused to raise the trolle into contact with the trolley wire. Whent e a1r in said cylinder is released, the trolley structure is caused to be retracted bya spring which is placed in tension by the extending of the trolley.

It has been found that, in releasing the trolley from contact with the trolley wire by exhausting the air from the cylinders, the structure collapses with considerable force, especially at the end of its downward travel, causing a severe blow when the trolle structure hits the stops on the car roo This causes ra id deterioration and destruction of the tro ley. Various means for eliminating this defect have been proposed but none of the devices were satisfactory for the purose. p The present invention is designed to obviate these difliculties, it being among the objects thereof to provide a pantographtrolley construction which shall be efiectlve in minimizing the blow which the trolley ordinarily receives when being retracted.

It is a further object of this invention to provide a structure which shall be simple, automatic in operation and capable of effectively stopping the downward travel of the trolley without allowing it to receive any substantial blow.

In practising my invention, I rovide the usual structure of actuating mec anism, including an air-actuated piston operating within a cylinder, and I secure thereto an auxiliary means which is adapted to trap a small amount of air in said cylinder to provide a temporary cushion which effectively a absorbs the shock or momentum of the down- Prefer-.

wardly moving trolley structure. ably, the device is in the form of a piston of small size relative to the main piston, having a leather cup in opposed relation to the leather cup of the main piston, and operating in a constricted end portion of the cy1ind er which serves for the entrance and exit of air.

In the'accompanying drawing constitutlng a part hereof, the single fi ure is a vertlcal sectlonal view of a cylinder such as is ordinarily used in "'pan'tograph trolleys, showing my lmprovement in place therein.

The cylinder 1 is provided with a constricted end portion 2 having an opening 3 there1n, 'a portion of which is threaded for connection thereof to a pipe-line 3 leading to a source of fluid pressure. A piston 4, havmga leather cup 5 interposed between the head 6 thereof and a covering plate 7 is held in place by tap screw 8. A boss 9 on the opposite end of the piston engages the cam surface 10 of lever 11 secured to shaft 12. The shaft 12 is operatively connected to a system of springs and levers adapted to raise and lower the trolley structure. One or more springs (not shown) are so secured to the system that they tend to force piston 4 in the direction of the restricted portion 2 of the cylinder 1.

Into the tap screw 8 is threaded a bolt 13 having thereon a leather cup 14 in opposed relation to leather cup 5. NVashers 15 and 16 are placed on the sides of leather cup 14, and nuts 17 and 18 are adapted to hold the same in place. An opening 19 is provided the members 14,- 15 and 16 to provide an air passage.

The operation of my device is as follows. Assuming that the trolley is in retracted position and it is desired to raise the same, air under pressure is caused to flow through the constricted end portion 2 of the cylinder 1, causing cup 14 to partially collapse and thus allow the air to flow past the same against the face of the piston 4. The full air pressure being exerted upon the piston 4, causes the same to move outwardly against the action of the spring or springs (not shown), causing shaft 12 to move and the pantograph trolley structure to be raised.

When it is desired to lower the trolley, the air pressure is cut otf and the air in the cylinder is permitted to escape from opening 3 to the atmosphere. The piston 4 thereupon moves towards the restricted end por tion 2, being biased by said springs in said direction. When the cup 14 enters the opening 3, the compression of the air trapped between cups 5 and 14 causes the latter to spread out and seal said air within a relatively small chamber, the efiect being that of a dash-pot which cushions the momentum of the downwardly moving trolley structure, thus avoiding a sharp blow.

I have found that my device is peculiarliy effective in accomplishing this result, avoi ing the necessity of auxiliary apparatus, such as rubber bumpers, spring or pneumatic shock absorbers or complicated structures, including air cylinders and the like for cushioning the blow. My device maybe readily adapted to' existing apparatus, it being mere- 1y necessary to tap the screw 8 and to ream the opening 3 for the reception of the leather Although I have described my invent-ion, setting forth a specific embodiment thereof,

it is to be understood that my invention is not limited to the details set forth. Various changes may be made in the constructionpf my device without departing from the principles of the invention as covered by the appended claims.

I claim as my invention: 1

1. The combination with a'cylinder having a constricted end portion, a piston therein and fluid means tor actuating said piston, of an auxiliary piston having a relatively small opening t erein secured to said flrst named piston and adapted to project into said constricted portion to restrict the passage of fluid from the cylinder into the con- 'stricted portion.

a 2. The combination with a cylinder havin a constricted end portion, of a piston within said cylinder, fluid means for actuating said piston, said means being connected to the constricted end portion of said cylinder, and an auxiliary piston having a relatively small opening therethrough adapted to project into the constricted portion to restrict the passage of fluid therethrough.

3.The combination with a cylinder, a piston therein, a cup of flexible material secured to said piston, and fluid means for actuatin said piston,v of an auxiliary piston secured to said first named piston and having a cup of flexible material secured there to in said cylinder for trapping fluid therein.

4. The combination with a cylinder, :1. piston therein, a cup of flexible material secured to said piston, and fluid means for actuating said piston, of'an auxiliary piston secured to said first named piston and having a cup of flexible material secured theretoin said cylinder for trapping fluid therein, said cups being in opposed relation.

5. The combination with a cylinder having a constricted end ortion, a piston therein and fluid means or actuating said iston, of means in said cylinder adapte to project into said constricted portion for fluid therein, said means comprising a bolt threaded into the head of said piston and an adjustable auxiliary piston carried thereby.

7. The combination with a cylinder having a constricted end portion,a piston therein and fluid means for actuating said piston,

of means in said cylinder adapted to projecv into said constricted portion for trapping fluid therein, said means comprising a bolt threaded into the head ofsaid piston and a leather cup adapted to fit in said constricted portion and carried by said piston.

8. The combination with a cylinder having a constricted end portion, a piston therein and fluid means for actuating said piston,

of means in said cylinder adapted to project into said constricted portion for trapping fluid therein, said means comprising a bolt threaded into the head of said piston and a leather cup adapted to fit in said constricted portion and. carried by said piston and held thereon by adjustable nuts.

9. The combination with a cylinder having a constricted end portion, a piston therein and fluid means for actuating said piston, of means in said cylinder adapted to project into said constricted portion for trapping fluid therein, said means comprising a bolt threaded into the head of said piston, a

leather cup adapted to fit in said constricted portion and carried by said piston and held thereon by nuts, and washers interposed between said cup and said nuts.

In testimony whereof, I have hereunto subscribed my name this 3rd day of November, 1922.

THOMAS S. PUKERUD. 

